It feels like, in this modern world, you shouldn't have to choose between having good sex and having good sleep, but apparently mattress consumers are, in fact, being faced with this dreadful choice. This is an issue because of memory-foam mattresses, which are becoming hugely popular as a result of their unique way of forming around your body and supporting you while you sleep. The only problem? They're terrible for having sex.

Unlike traditional spring mattresses, which offer plenty of support off of which to launch your sexual moves, memory foam is a bit too squishy. According to sex therapist Sari Eckler Cooper, who spoke to Barron's, "There's a lack of resistance for the knees and feet. And whoever is on the bottom is sinking into the bed." Nothing like a little quicksand sex to finish off a night…

Still, the prospect of more challenging sex has not stopped people from buying memory foam mattresses in droves. They're the fastest growing segment in the mattress market, and their market share has gone up considerably in the past eight years. Looks like people care more about getting good sleep than getting good sex. Of course, it's easy to have sex on any number of other surfaces, but it's not so simple to get a good night's sleep on the floor or the kitchen counter—so perhaps it is wise to go for a mattress that's optimized for slumber.